Western U.S. oil shales could produce millions of barrels of oil per day in 20 to 30 years if technological, environmental and governance issues are resolved. This is according to a study by the Rand Environment, Energy and Economic Development program, a subsidiary of The Rand Corp. Oil shale contains petroleum-like solids that are released when the rock is heated. The high cost of mining has made them uneconomical but if today's high prices continue, production could be part of future world energy supply, the report says. An initial round of commercial oil-shale facilities could test feasibility. In-situ conversion, which involves heating oil shale while in the ground, eliminates the need for mining, making oil shale less damaging to surface topography and the environment, the report says. If production is feasible, Rand estimates between 500 billion and 1.1 trillion barrels of oil could be recoverable from high-grade deposits in the Green River formation in Colorado, Utah and Wyoming. This is approximately three times Saudi Arabia's reserves. The researchers estimate the shales could provide enough oil to meet 25% of America's oil demand for the next 400 years. They estimate that shale-oil production of 3 million barrels per day could cause oil prices to fall by between 3% and 5%.